diff --git a/master.cfg b/master.cfg
index 7df5bd9..3209786 100644
--- a/master.cfg
+++ b/master.cfg
@@ -330,7 +330,7 @@ def generic_builder(id, libdir='', branch='', rsync=False):
                              maxsize=180 * 1024 * 1024,
                              workdir='install'))
     f.addStep(MasterShellCommand(name='unpack',
-                                 command=['python2.7',
+                                 command=['python3.6',
                                           unpack_script,
                                           filename],
                                  description='unpacking',